1. 3-2 What Keeps Us and Other Organisms Alive?
Concept 3-2 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

2. Earth Has Four Major Life-Support Components
Atmosphere
Hydrosphere
Geosphere
Biosphere

3. General Structure of the Earth

4. Vegetation and animals Atmosphere Biosphere Soil Rock Crust
Lithosphere
Mantle
Biosphere
(living organisms)
Figure 3.5: Natural capital: general structure of the earth.
Core
Atmosphere
(air)
Mantle
Crust
(soil and rock)
Geosphere
(crust, mantle, core)
Hydrosphere
(water)
Fig. 3-5, p. 42

5. Classification of the Biosphere
Biomes – terrestrial regions with similar vegetation
Aquatic life zones
Freshwater life zones
Marine life zones

6. Biomes of the United States

7. Coastal mountain ranges Sierra Nevada Great American Desert Rocky
Mountains
Great
Plains
Mississippi
River Valley
Appalachian
Mountains
Figure 3.6: Major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature.
Coastal chaparral
and scrub
Coniferous forest
Desert
Coniferous forest
Prairie grassland
Deciduous forest
Fig. 3-6, p. 43

8. Three Factors Sustain Life on Earth
One-way flow of high-quality energy from the sun
Cycling of matter or nutrients through parts of the biosphere
Gravity

9. Solar Energy Reaching the Earth
Electromagnetic waves
Visible light
UV radiation
Heat
Natural greenhouse effect
Energy in = energy out
Human-enhanced global warming

10. Solar Capital

11. Solar radiation Lower Stratosphere (ozone layer) Greenhouse effect
Energy in = Energy out
Reflected by
atmosphere
UV radiation
Radiated by
atmosphere
as heat
Lower Stratosphere
(ozone layer)
Most
absorbed
by ozone
Visible
light
Troposphere
Heat radiated
by the earth
Heat
Figure 3.7: Solar capital: flow of energy to and from the earth.
See an animation based on this figure at ThomsonNOW.
Absorbed
by the earth
Greenhouse
effect
Fig. 3-7, p. 44